The invention relates to a tool for preventing rotation of a tubing string or progressive cavity pump in the bore of a casing string.
Oil is often pumped from a subterranean reservoir using a progressive cavity (PC) pump. The stator of the PC pump is threaded onto the bottom of a long assembled string of sectional tubing. A rod string extends downhole and drives the PC pump rotor. Large reaction or rotor rotational forces can cause the tubing or PC pump stator to unthread, resulting in loss of the pump or tubing string.
Anti-rotation tools are known including Canadian Patent No. 1,274,470 to J. L. Weber and U.S. Pat. No. 5,275,239 to M. Obrejanu. These tools use a plurality of moving components, slips and springs to anchor and centralize the PC Pump stator in the well casing.
Further, the eccentric rotation of the PC Pump rotor imposes cyclical motion of the PC Pump stator, which in many cases is supported or restrained solely by the tool""s slips. Occasionally a stabilizing tool is added to dampen or restrain the cyclical motion to failure of the anti-rotation tool.
A simplified anti-rotation tool is provided, having only one jaw as a moving part but which both prevents rotation and stabilizes that to which it is connected. In simplistic terms, the tool connects to a progressive cavity (PC) pump or other downhole tool. Upon rotation of the tool in one direction a jaw, which is biased outwardly from the tool housing, engages the casing wall to arrest tool rotation. This action causes the tool housing to move oppositely and come to rest against the casing opposing the jaw. The tool housing and the downhole tool are thereby restrained and stabilized by the casing wall.
In a broad apparatus aspect, an anti-rotation tool comprises: a tubular housing having a bore and having at least one end for connection to a downhole tool and a jaw having a hinge and a radial tip. The jaw is pivoted at its hinge from one side of the housing, so that the jaw is biased so as to pivot outwardly to a first casing-engaging position, wherein the radial tip engages the casing, and the housing is urged against the casing opposite the jaw. The jaw is also inwardly pivotable to a second compressed position towards the housing to enable movement within the casing during tripping in and tripping out.
Preferably, the jaw is biased to the casing-engaging position by a torsional member extending through the hinge, which is rigidly connected to the housing at a first end and to the jaw at a second end. Compression of the jaw twists the torsional member into torsion which then acts to bias or urge the jaw outwardly again.
Preferably, the swing of the jaw is arranged for tools having conventional threaded connections wherein the jaw is actuated under clockwise rotation and is compressed by counter clockwise rotation of the tool.
More preferably, the jaw is formed separately from the housing so that the housing and bore remain independent and the bore can conduct fluid.